Repeated sleep restriction in rats leads to homeostatic and allostatic responses during recovery sleep

Abstract

Recent studies indicate that chronic sleep restriction can have negative consequences for brain function and peripheral physiology and can contribute to the allostatic load throughout the body. Interestingly, few studies have examined how the sleep-wake system itself responds to repeated sleep restriction. In this study, rats were subjected to a sleep-restriction protocol consisting of 20 h of sleep deprivation (SD) followed by a 4-h sleep opportunity each day for 5 consecutive days. In response to the first 20-h SD block on day 1, animals responded during the 4-h sleep opportunity with enhanced sleep intensity [i.e., nonrapid eye movement (NREM) delta power] and increased rapid eye movement sleep time compared with baseline. This sleep pattern is indicative of a homeostatic response to acute sleep loss. Remarkably, after the 20-h SD blocks on days 2-5, animals failed to exhibit a compensatory NREM delta power response during the 4-h sleep opportunities and failed to increase NREM and rapid eye movement sleep times, despite accumulating a sleep debt each consecutive day. After losing Ϸ35 h of sleep over 5 days of sleep restriction, animals regained virtually none of their lost sleep, even during a full 3-day recovery period. These data demonstrate that the compensatory/ homeostatic sleep response to acute SD does not generalize to conditions of chronic partial sleep loss. We propose that the change in sleep-wake regulation in the context of repeated sleep restriction reflects an allostatic process, and that the allostatic load produced by SD has direct effects on the sleep-wake regulatory system. allostasis ͉ homeostasis ͉ sleep deprivation ͉ stress ͉ rodents

Doing with less sleep remains a dream

“…Their findings lead to a different conclusion than the report of Kim et al (1) and suggest that the methods of enforcing wakefulness and of assessing the effects of sleep deprivation that we have traditionally relied on in shortterm protocols may not apply in chronic sleep restriction protocols.…”

“…Three years ago, a PNAS report by Kim et al (1) gave some hope. Their findings suggested that rats gradually lowered their homeostatic set point, so that they actually learned to do with less sleep if exposed to chronic sleep restriction for several days rather than acute sleep deprivation for a single day.…”

Effects of three weeks of mild sleep restriction implemented in the home environment on multiple metabolic and endocrine markers in healthy young men

“…we had truncated the study at 1 week, we too would have reported a significant impairment in insulin sensitivity (difference in IS between groups at one week; 2.55mg -1 .kg -1 .min, However, multiple rodent studies have found adaptations or lack of NREMS SWA responses after chronic sleep restriction [30,31] [32,33], indeed in humans, adaptation in NREMS SWA responses has been reported to increase very little after sleep restriction [34] for four or five nights [35] . Although comparison between human and rodent studies should always be 15 made with some trepidation, and whether the mild sleep restriction in this study would allow for some adaptation to occur, can only be determined by sleep EEG recordings…”

Sleep and circadian rhythms: Key components in the regulation of energy metabolism

“…We have recently developed a model of chronic partial sleep restriction in rats and have made the novel discovery that following repeated days of sleep loss, rats lose the ability to generate a homeostatic sleep response, as depicted in Fig. 1 [34]. We propose that this pattern is indicative of a change in the recovery strategy from homeostasis to allostasis [35].…”